查询应用程序开发的设计指南

I have a wizard application for MS Windows which is a typical Next-Next-Finish type. The application has a default vendor specific window background theme which persists through all the windows of the application (i.e Vendor logo and background color for each screen). I want to develop a similar application wizard for Mac. I noticed that all the applications have a default Grey colored window in Mac. Is there any design guideline provided by Apple which states that the background color of the windows must be the default? Can I use custom colors and images for the application? Any ideas will be highly appreciated.I have a wizard application for MS Windows whic